Merge remote-tracking branch 'rcu/rcu/next'
[deliverable/linux.git] / kernel / pid.c
CommitLineData
1da177e4
LT
1/*
2 * Generic pidhash and scalable, time-bounded PID allocator
3 *
6d49e352
NYC
4 * (C) 2002-2003 Nadia Yvette Chambers, IBM
5 * (C) 2004 Nadia Yvette Chambers, Oracle
1da177e4
LT
6 * (C) 2002-2004 Ingo Molnar, Red Hat
7 *
8 * pid-structures are backing objects for tasks sharing a given ID to chain
9 * against. There is very little to them aside from hashing them and
10 * parking tasks using given ID's on a list.
11 *
12 * The hash is always changed with the tasklist_lock write-acquired,
13 * and the hash is only accessed with the tasklist_lock at least
14 * read-acquired, so there's no additional SMP locking needed here.
15 *
16 * We have a list of bitmap pages, which bitmaps represent the PID space.
17 * Allocating and freeing PIDs is completely lockless. The worst-case
18 * allocation scenario when all but one out of 1 million PIDs possible are
19 * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
20 * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
30e49c26
PE
21 *
22 * Pid namespaces:
23 * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
24 * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
25 * Many thanks to Oleg Nesterov for comments and help
26 *
1da177e4
LT
27 */
28
29#include <linux/mm.h>
9984de1a 30#include <linux/export.h>
1da177e4
LT
31#include <linux/slab.h>
32#include <linux/init.h>
82524746 33#include <linux/rculist.h>
1da177e4
LT
34#include <linux/bootmem.h>
35#include <linux/hash.h>
61a58c6c 36#include <linux/pid_namespace.h>
820e45db 37#include <linux/init_task.h>
3eb07c8c 38#include <linux/syscalls.h>
0bb80f24 39#include <linux/proc_ns.h>
0a01f2cc 40#include <linux/proc_fs.h>
1da177e4 41
8ef047aa
PE
42#define pid_hashfn(nr, ns) \
43 hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
92476d7f 44static struct hlist_head *pid_hash;
2c85f51d 45static unsigned int pidhash_shift = 4;
820e45db 46struct pid init_struct_pid = INIT_STRUCT_PID;
1da177e4
LT
47
48int pid_max = PID_MAX_DEFAULT;
1da177e4
LT
49
50#define RESERVED_PIDS 300
51
52int pid_max_min = RESERVED_PIDS + 1;
53int pid_max_max = PID_MAX_LIMIT;
54
61a58c6c
SB
55static inline int mk_pid(struct pid_namespace *pid_ns,
56 struct pidmap *map, int off)
3fbc9648 57{
61a58c6c 58 return (map - pid_ns->pidmap)*BITS_PER_PAGE + off;
3fbc9648
SB
59}
60
1da177e4
LT
61#define find_next_offset(map, off) \
62 find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
63
64/*
65 * PID-map pages start out as NULL, they get allocated upon
66 * first use and are never deallocated. This way a low pid_max
67 * value does not cause lots of bitmaps to be allocated, but
68 * the scheme scales to up to 4 million PIDs, runtime.
69 */
61a58c6c 70struct pid_namespace init_pid_ns = {
9a575a92
CLG
71 .kref = {
72 .refcount = ATOMIC_INIT(2),
73 },
3fbc9648
SB
74 .pidmap = {
75 [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
76 },
84d73786 77 .last_pid = 0,
8f75af44 78 .nr_hashed = PIDNS_HASH_ADDING,
faacbfd3
PE
79 .level = 0,
80 .child_reaper = &init_task,
49f4d8b9 81 .user_ns = &init_user_ns,
435d5f4b 82 .ns.inum = PROC_PID_INIT_INO,
33c42940
AV
83#ifdef CONFIG_PID_NS
84 .ns.ops = &pidns_operations,
85#endif
3fbc9648 86};
198fe21b 87EXPORT_SYMBOL_GPL(init_pid_ns);
1da177e4 88
92476d7f
EB
89/*
90 * Note: disable interrupts while the pidmap_lock is held as an
91 * interrupt might come in and do read_lock(&tasklist_lock).
92 *
93 * If we don't disable interrupts there is a nasty deadlock between
94 * detach_pid()->free_pid() and another cpu that does
95 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
96 * read_lock(&tasklist_lock);
97 *
98 * After we clean up the tasklist_lock and know there are no
99 * irq handlers that take it we can leave the interrupts enabled.
100 * For now it is easier to be safe than to prove it can't happen.
101 */
3fbc9648 102
1da177e4
LT
103static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
104
b7127aa4 105static void free_pidmap(struct upid *upid)
1da177e4 106{
b7127aa4
ON
107 int nr = upid->nr;
108 struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE;
109 int offset = nr & BITS_PER_PAGE_MASK;
1da177e4
LT
110
111 clear_bit(offset, map->page);
112 atomic_inc(&map->nr_free);
113}
114
5fdee8c4
S
115/*
116 * If we started walking pids at 'base', is 'a' seen before 'b'?
117 */
118static int pid_before(int base, int a, int b)
119{
120 /*
121 * This is the same as saying
122 *
123 * (a - base + MAXUINT) % MAXUINT < (b - base + MAXUINT) % MAXUINT
124 * and that mapping orders 'a' and 'b' with respect to 'base'.
125 */
126 return (unsigned)(a - base) < (unsigned)(b - base);
127}
128
129/*
b8f566b0
PE
130 * We might be racing with someone else trying to set pid_ns->last_pid
131 * at the pid allocation time (there's also a sysctl for this, but racing
132 * with this one is OK, see comment in kernel/pid_namespace.c about it).
5fdee8c4
S
133 * We want the winner to have the "later" value, because if the
134 * "earlier" value prevails, then a pid may get reused immediately.
135 *
136 * Since pids rollover, it is not sufficient to just pick the bigger
137 * value. We have to consider where we started counting from.
138 *
139 * 'base' is the value of pid_ns->last_pid that we observed when
140 * we started looking for a pid.
141 *
142 * 'pid' is the pid that we eventually found.
143 */
144static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid)
145{
146 int prev;
147 int last_write = base;
148 do {
149 prev = last_write;
150 last_write = cmpxchg(&pid_ns->last_pid, prev, pid);
151 } while ((prev != last_write) && (pid_before(base, last_write, pid)));
152}
153
61a58c6c 154static int alloc_pidmap(struct pid_namespace *pid_ns)
1da177e4 155{
61a58c6c 156 int i, offset, max_scan, pid, last = pid_ns->last_pid;
6a1f3b84 157 struct pidmap *map;
1da177e4
LT
158
159 pid = last + 1;
160 if (pid >= pid_max)
161 pid = RESERVED_PIDS;
162 offset = pid & BITS_PER_PAGE_MASK;
61a58c6c 163 map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
c52b0b91
ON
164 /*
165 * If last_pid points into the middle of the map->page we
166 * want to scan this bitmap block twice, the second time
167 * we start with offset == 0 (or RESERVED_PIDS).
168 */
169 max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset;
1da177e4
LT
170 for (i = 0; i <= max_scan; ++i) {
171 if (unlikely(!map->page)) {
3fbc9648 172 void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
1da177e4
LT
173 /*
174 * Free the page if someone raced with us
175 * installing it:
176 */
92476d7f 177 spin_lock_irq(&pidmap_lock);
7be6d991 178 if (!map->page) {
3fbc9648 179 map->page = page;
7be6d991
AGR
180 page = NULL;
181 }
92476d7f 182 spin_unlock_irq(&pidmap_lock);
7be6d991 183 kfree(page);
1da177e4 184 if (unlikely(!map->page))
35f71bc0 185 return -ENOMEM;
1da177e4
LT
186 }
187 if (likely(atomic_read(&map->nr_free))) {
8db049b3 188 for ( ; ; ) {
1da177e4
LT
189 if (!test_and_set_bit(offset, map->page)) {
190 atomic_dec(&map->nr_free);
5fdee8c4 191 set_last_pid(pid_ns, last, pid);
1da177e4
LT
192 return pid;
193 }
194 offset = find_next_offset(map, offset);
8db049b3
RC
195 if (offset >= BITS_PER_PAGE)
196 break;
61a58c6c 197 pid = mk_pid(pid_ns, map, offset);
8db049b3
RC
198 if (pid >= pid_max)
199 break;
200 }
1da177e4 201 }
61a58c6c 202 if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
1da177e4
LT
203 ++map;
204 offset = 0;
205 } else {
61a58c6c 206 map = &pid_ns->pidmap[0];
1da177e4
LT
207 offset = RESERVED_PIDS;
208 if (unlikely(last == offset))
209 break;
210 }
61a58c6c 211 pid = mk_pid(pid_ns, map, offset);
1da177e4 212 }
35f71bc0 213 return -EAGAIN;
1da177e4
LT
214}
215
c78193e9 216int next_pidmap(struct pid_namespace *pid_ns, unsigned int last)
0804ef4b
EB
217{
218 int offset;
f40f50d3 219 struct pidmap *map, *end;
0804ef4b 220
c78193e9
LT
221 if (last >= PID_MAX_LIMIT)
222 return -1;
223
0804ef4b 224 offset = (last + 1) & BITS_PER_PAGE_MASK;
61a58c6c
SB
225 map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
226 end = &pid_ns->pidmap[PIDMAP_ENTRIES];
f40f50d3 227 for (; map < end; map++, offset = 0) {
0804ef4b
EB
228 if (unlikely(!map->page))
229 continue;
230 offset = find_next_bit((map)->page, BITS_PER_PAGE, offset);
231 if (offset < BITS_PER_PAGE)
61a58c6c 232 return mk_pid(pid_ns, map, offset);
0804ef4b
EB
233 }
234 return -1;
235}
236
7ad5b3a5 237void put_pid(struct pid *pid)
92476d7f 238{
baf8f0f8
PE
239 struct pid_namespace *ns;
240
92476d7f
EB
241 if (!pid)
242 return;
baf8f0f8 243
8ef047aa 244 ns = pid->numbers[pid->level].ns;
92476d7f 245 if ((atomic_read(&pid->count) == 1) ||
8ef047aa 246 atomic_dec_and_test(&pid->count)) {
baf8f0f8 247 kmem_cache_free(ns->pid_cachep, pid);
b461cc03 248 put_pid_ns(ns);
8ef047aa 249 }
92476d7f 250}
bbf73147 251EXPORT_SYMBOL_GPL(put_pid);
92476d7f
EB
252
253static void delayed_put_pid(struct rcu_head *rhp)
254{
255 struct pid *pid = container_of(rhp, struct pid, rcu);
256 put_pid(pid);
257}
258
7ad5b3a5 259void free_pid(struct pid *pid)
92476d7f
EB
260{
261 /* We can be called with write_lock_irq(&tasklist_lock) held */
8ef047aa 262 int i;
92476d7f
EB
263 unsigned long flags;
264
265 spin_lock_irqsave(&pidmap_lock, flags);
0a01f2cc
EB
266 for (i = 0; i <= pid->level; i++) {
267 struct upid *upid = pid->numbers + i;
af4b8a83 268 struct pid_namespace *ns = upid->ns;
0a01f2cc 269 hlist_del_rcu(&upid->pid_chain);
af4b8a83 270 switch(--ns->nr_hashed) {
a6064885 271 case 2:
af4b8a83
EB
272 case 1:
273 /* When all that is left in the pid namespace
274 * is the reaper wake up the reaper. The reaper
275 * may be sleeping in zap_pid_ns_processes().
276 */
277 wake_up_process(ns->child_reaper);
278 break;
314a8ad0
ON
279 case PIDNS_HASH_ADDING:
280 /* Handle a fork failure of the first process */
281 WARN_ON(ns->child_reaper);
282 ns->nr_hashed = 0;
283 /* fall through */
af4b8a83 284 case 0:
af4b8a83
EB
285 schedule_work(&ns->proc_work);
286 break;
5e1182de 287 }
0a01f2cc 288 }
92476d7f
EB
289 spin_unlock_irqrestore(&pidmap_lock, flags);
290
8ef047aa 291 for (i = 0; i <= pid->level; i++)
b7127aa4 292 free_pidmap(pid->numbers + i);
8ef047aa 293
92476d7f
EB
294 call_rcu(&pid->rcu, delayed_put_pid);
295}
296
8ef047aa 297struct pid *alloc_pid(struct pid_namespace *ns)
92476d7f
EB
298{
299 struct pid *pid;
300 enum pid_type type;
8ef047aa
PE
301 int i, nr;
302 struct pid_namespace *tmp;
198fe21b 303 struct upid *upid;
35f71bc0 304 int retval = -ENOMEM;
92476d7f 305
baf8f0f8 306 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
92476d7f 307 if (!pid)
35f71bc0 308 return ERR_PTR(retval);
92476d7f 309
8ef047aa 310 tmp = ns;
0a01f2cc 311 pid->level = ns->level;
8ef047aa
PE
312 for (i = ns->level; i >= 0; i--) {
313 nr = alloc_pidmap(tmp);
287980e4 314 if (nr < 0) {
35f71bc0 315 retval = nr;
8ef047aa 316 goto out_free;
35f71bc0 317 }
92476d7f 318
8ef047aa
PE
319 pid->numbers[i].nr = nr;
320 pid->numbers[i].ns = tmp;
321 tmp = tmp->parent;
322 }
323
0a01f2cc
EB
324 if (unlikely(is_child_reaper(pid))) {
325 if (pid_ns_prepare_proc(ns))
326 goto out_free;
327 }
328
b461cc03 329 get_pid_ns(ns);
92476d7f 330 atomic_set(&pid->count, 1);
92476d7f
EB
331 for (type = 0; type < PIDTYPE_MAX; ++type)
332 INIT_HLIST_HEAD(&pid->tasks[type]);
333
417e3152 334 upid = pid->numbers + ns->level;
92476d7f 335 spin_lock_irq(&pidmap_lock);
c876ad76 336 if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
5e1182de 337 goto out_unlock;
0a01f2cc 338 for ( ; upid >= pid->numbers; --upid) {
198fe21b
PE
339 hlist_add_head_rcu(&upid->pid_chain,
340 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
0a01f2cc
EB
341 upid->ns->nr_hashed++;
342 }
92476d7f
EB
343 spin_unlock_irq(&pidmap_lock);
344
92476d7f
EB
345 return pid;
346
5e1182de 347out_unlock:
6e666884 348 spin_unlock_irq(&pidmap_lock);
24c037eb
ON
349 put_pid_ns(ns);
350
92476d7f 351out_free:
b7127aa4
ON
352 while (++i <= ns->level)
353 free_pidmap(pid->numbers + i);
8ef047aa 354
baf8f0f8 355 kmem_cache_free(ns->pid_cachep, pid);
35f71bc0 356 return ERR_PTR(retval);
92476d7f
EB
357}
358
c876ad76
EB
359void disable_pid_allocation(struct pid_namespace *ns)
360{
361 spin_lock_irq(&pidmap_lock);
362 ns->nr_hashed &= ~PIDNS_HASH_ADDING;
363 spin_unlock_irq(&pidmap_lock);
364}
365
7ad5b3a5 366struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
1da177e4 367{
198fe21b
PE
368 struct upid *pnr;
369
b67bfe0d 370 hlist_for_each_entry_rcu(pnr,
198fe21b
PE
371 &pid_hash[pid_hashfn(nr, ns)], pid_chain)
372 if (pnr->nr == nr && pnr->ns == ns)
373 return container_of(pnr, struct pid,
374 numbers[ns->level]);
1da177e4 375
1da177e4
LT
376 return NULL;
377}
198fe21b 378EXPORT_SYMBOL_GPL(find_pid_ns);
1da177e4 379
8990571e
PE
380struct pid *find_vpid(int nr)
381{
17cf22c3 382 return find_pid_ns(nr, task_active_pid_ns(current));
8990571e
PE
383}
384EXPORT_SYMBOL_GPL(find_vpid);
385
e713d0da
SB
386/*
387 * attach_pid() must be called with the tasklist_lock write-held.
388 */
81907739 389void attach_pid(struct task_struct *task, enum pid_type type)
1da177e4 390{
81907739
ON
391 struct pid_link *link = &task->pids[type];
392 hlist_add_head_rcu(&link->node, &link->pid->tasks[type]);
1da177e4
LT
393}
394
24336eae
ON
395static void __change_pid(struct task_struct *task, enum pid_type type,
396 struct pid *new)
1da177e4 397{
92476d7f
EB
398 struct pid_link *link;
399 struct pid *pid;
400 int tmp;
1da177e4 401
92476d7f
EB
402 link = &task->pids[type];
403 pid = link->pid;
1da177e4 404
92476d7f 405 hlist_del_rcu(&link->node);
24336eae 406 link->pid = new;
1da177e4 407
92476d7f
EB
408 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
409 if (!hlist_empty(&pid->tasks[tmp]))
410 return;
1da177e4 411
92476d7f 412 free_pid(pid);
1da177e4
LT
413}
414
24336eae
ON
415void detach_pid(struct task_struct *task, enum pid_type type)
416{
417 __change_pid(task, type, NULL);
418}
419
420void change_pid(struct task_struct *task, enum pid_type type,
421 struct pid *pid)
422{
423 __change_pid(task, type, pid);
81907739 424 attach_pid(task, type);
24336eae
ON
425}
426
c18258c6 427/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
7ad5b3a5 428void transfer_pid(struct task_struct *old, struct task_struct *new,
c18258c6
EB
429 enum pid_type type)
430{
431 new->pids[type].pid = old->pids[type].pid;
432 hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
c18258c6
EB
433}
434
7ad5b3a5 435struct task_struct *pid_task(struct pid *pid, enum pid_type type)
1da177e4 436{
92476d7f
EB
437 struct task_struct *result = NULL;
438 if (pid) {
439 struct hlist_node *first;
67bdbffd 440 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
db1466b3 441 lockdep_tasklist_lock_is_held());
92476d7f
EB
442 if (first)
443 result = hlist_entry(first, struct task_struct, pids[(type)].node);
444 }
445 return result;
446}
eccba068 447EXPORT_SYMBOL(pid_task);
1da177e4 448
92476d7f 449/*
9728e5d6 450 * Must be called under rcu_read_lock().
92476d7f 451 */
17f98dcf 452struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
92476d7f 453{
f78f5b90
PM
454 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
455 "find_task_by_pid_ns() needs rcu_read_lock() protection");
17f98dcf 456 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
92476d7f 457}
1da177e4 458
228ebcbe
PE
459struct task_struct *find_task_by_vpid(pid_t vnr)
460{
17cf22c3 461 return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
228ebcbe 462}
228ebcbe 463
1a657f78
ON
464struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
465{
466 struct pid *pid;
467 rcu_read_lock();
2ae448ef
ON
468 if (type != PIDTYPE_PID)
469 task = task->group_leader;
81b1a832 470 pid = get_pid(rcu_dereference(task->pids[type].pid));
1a657f78
ON
471 rcu_read_unlock();
472 return pid;
473}
77c100c8 474EXPORT_SYMBOL_GPL(get_task_pid);
1a657f78 475
7ad5b3a5 476struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
92476d7f
EB
477{
478 struct task_struct *result;
479 rcu_read_lock();
480 result = pid_task(pid, type);
481 if (result)
482 get_task_struct(result);
483 rcu_read_unlock();
484 return result;
1da177e4 485}
77c100c8 486EXPORT_SYMBOL_GPL(get_pid_task);
1da177e4 487
92476d7f 488struct pid *find_get_pid(pid_t nr)
1da177e4
LT
489{
490 struct pid *pid;
491
92476d7f 492 rcu_read_lock();
198fe21b 493 pid = get_pid(find_vpid(nr));
92476d7f 494 rcu_read_unlock();
1da177e4 495
92476d7f 496 return pid;
1da177e4 497}
339caf2a 498EXPORT_SYMBOL_GPL(find_get_pid);
1da177e4 499
7af57294
PE
500pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
501{
502 struct upid *upid;
503 pid_t nr = 0;
504
505 if (pid && ns->level <= pid->level) {
506 upid = &pid->numbers[ns->level];
507 if (upid->ns == ns)
508 nr = upid->nr;
509 }
510 return nr;
511}
4f82f457 512EXPORT_SYMBOL_GPL(pid_nr_ns);
7af57294 513
44c4e1b2
EB
514pid_t pid_vnr(struct pid *pid)
515{
17cf22c3 516 return pid_nr_ns(pid, task_active_pid_ns(current));
44c4e1b2
EB
517}
518EXPORT_SYMBOL_GPL(pid_vnr);
519
52ee2dfd
ON
520pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
521 struct pid_namespace *ns)
2f2a3a46 522{
52ee2dfd
ON
523 pid_t nr = 0;
524
525 rcu_read_lock();
526 if (!ns)
17cf22c3 527 ns = task_active_pid_ns(current);
52ee2dfd
ON
528 if (likely(pid_alive(task))) {
529 if (type != PIDTYPE_PID)
530 task = task->group_leader;
81b1a832 531 nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
52ee2dfd
ON
532 }
533 rcu_read_unlock();
534
535 return nr;
2f2a3a46 536}
52ee2dfd 537EXPORT_SYMBOL(__task_pid_nr_ns);
2f2a3a46
PE
538
539pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
540{
541 return pid_nr_ns(task_tgid(tsk), ns);
542}
543EXPORT_SYMBOL(task_tgid_nr_ns);
544
61bce0f1
EB
545struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
546{
547 return ns_of_pid(task_pid(tsk));
548}
549EXPORT_SYMBOL_GPL(task_active_pid_ns);
550
0804ef4b 551/*
025dfdaf 552 * Used by proc to find the first pid that is greater than or equal to nr.
0804ef4b 553 *
e49859e7 554 * If there is a pid at nr this function is exactly the same as find_pid_ns.
0804ef4b 555 */
198fe21b 556struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
0804ef4b
EB
557{
558 struct pid *pid;
559
560 do {
198fe21b 561 pid = find_pid_ns(nr, ns);
0804ef4b
EB
562 if (pid)
563 break;
198fe21b 564 nr = next_pidmap(ns, nr);
0804ef4b
EB
565 } while (nr > 0);
566
567 return pid;
568}
569
1da177e4
LT
570/*
571 * The pid hash table is scaled according to the amount of memory in the
572 * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or
573 * more.
574 */
575void __init pidhash_init(void)
576{
074b8517 577 unsigned int i, pidhash_size;
1da177e4 578
2c85f51d
JB
579 pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
580 HASH_EARLY | HASH_SMALL,
31fe62b9
TB
581 &pidhash_shift, NULL,
582 0, 4096);
074b8517 583 pidhash_size = 1U << pidhash_shift;
1da177e4 584
92476d7f
EB
585 for (i = 0; i < pidhash_size; i++)
586 INIT_HLIST_HEAD(&pid_hash[i]);
1da177e4
LT
587}
588
589void __init pidmap_init(void)
590{
840d6fe7 591 /* Verify no one has done anything silly: */
c876ad76
EB
592 BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);
593
72680a19
HB
594 /* bump default and minimum pid_max based on number of cpus */
595 pid_max = min(pid_max_max, max_t(int, pid_max,
596 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
597 pid_max_min = max_t(int, pid_max_min,
598 PIDS_PER_CPU_MIN * num_possible_cpus());
599 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
600
61a58c6c 601 init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
73b9ebfe 602 /* Reserve PID 0. We never call free_pidmap(0) */
61a58c6c
SB
603 set_bit(0, init_pid_ns.pidmap[0].page);
604 atomic_dec(&init_pid_ns.pidmap[0].nr_free);
92476d7f 605
74bd59bb 606 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
5d097056 607 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
1da177e4 608}
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